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CN-122003461-A - Recycle process for recovery of epsilon-caprolactam from solid material

CN122003461ACN 122003461 ACN122003461 ACN 122003461ACN-122003461-A

Abstract

The invention relates to a recycling process for recovering epsilon caprolactam from a solid material W comprising polyamide 6, which process comprises pyrolyzing the solid material W and subsequently subjecting it to further treatment to recover valuable epsilon caprolactam.

Inventors

  • A. Languede Oliveira
  • O. Pilarsky
  • S. MILLER
  • M. FRANK
  • HIEBER GISELA
  • D. Kepuke
  • P. NEWMAN

Assignees

  • 巴斯夫欧洲公司

Dates

Publication Date
20260508
Application Date
20241010
Priority Date
20231011

Claims (15)

  1. 1. A recycling process for recovering epsilon caprolactam from a solid material W comprising polyamide 6, the process comprising (I) Providing the solid material W; (ii) Subjecting the solid material W provided according to (i) to a pyrolysis, preferably anhydrous, in a pyrolysis reactor unit RU (P), obtaining a mixture MP comprising: An aqueous phase PA (1) comprising epsilon-caprolactam, -An organic phase PO (1) comprising epsilon-caprolactam; (iii) Separating epsilon caprolactam from MP obtained according to (ii), (iii) comprising (Iii.1) passing the mixture MP obtained according to (ii) into a separation unit SU obtaining a liquid stream S1 comprising PO (1) and a liquid stream S2 comprising PA (1); (iii.2) separating epsilon caprolactam from the liquid stream S2 obtained according to (iii.1) in a purification unit PU.
  2. 2. The method of claim 1, wherein the solid material W comprises polyamide 6 in an amount of at least 0.25 weight-%, preferably at least 1 weight-%, more preferably in the range of 1 to 95 weight-%, more preferably in the range of 2 to 80 weight-%, more preferably in the range of 3 to 60 weight-%, based on the weight of W.
  3. 3. The method of claim 1 or 2, wherein the solid material W comprises solid waste, wherein said waste preferably comprises one or more of plastic waste and textile waste; Wherein preferably the solid material W comprises one or more polyolefins in addition to polyamide 6.
  4. 4. A process as claimed in any one of claims 1 to 3, wherein the pyrolysis according to (ii) is carried out by thermal and/or catalytic cracking.
  5. 5. The process of any one of claims 1 to 4, wherein the pyrolysis according to (ii) is carried out at a temperature in the range of 250 ℃ to 800 ℃, preferably in the range of 300 ℃ to 700 ℃, more preferably in the range of 350 ℃ to 650 ℃, more preferably in the range of 400 ℃ to 600 ℃; wherein the pyrolysis according to (ii) is preferably carried out at a pressure in the range of 0.1 to 5 bar (absolute), more preferably in the range of 0.9 to 1.5 bar (absolute).
  6. 6. The method of any one of claims 1 to 5, wherein (ii) comprises (Ii.1) subjecting W to pyrolysis in a pyrolysis reactor unit RU (P), obtaining an intermediate gas stream G; (ii.2) subjecting the intermediate gas stream G to condensation in a gas-liquid separation unit to obtain a mixture MP comprising An aqueous phase PA (1) comprising epsilon-caprolactam, An organic phase PO (1) comprising epsilon-caprolactam, Wherein the condensation according to (ii.2) is carried out at a temperature preferably in the range of 20 ℃ to 300 ℃, more preferably in the range of 70 ℃ to 110 ℃.
  7. 7. Process according to any one of claims 1 to 6, wherein 50 to 99.9 wt-%, preferably 70 to 98 wt-%, more preferably 80 to 95 wt-% of epsilon caprolactam comprised in MP is in the aqueous phase PA (1) obtained according to (ii).
  8. 8. The process according to any one of claims 1 to 7, wherein passing the mixture MP obtained according to (ii) into a separation unit SU according to (iii.1) to obtain a liquid stream S1 comprising PO (1) and a liquid stream S2 comprising PA (1) comprises (Iii.1.1) passing the mixture MP obtained according to (ii) into a solid-liquid separation subunit SU1 comprised in SU to remove solids comprised in MP, obtaining a liquid mixture MP1 which is lean in solids compared to MP; (iii.1.2) passing the liquid mixture MP1 obtained according to (iii.1.1) into a liquid-liquid separation subunit SU2 comprised in SU, SU2 being located downstream of SU1, obtaining the liquid stream S1 comprising PO (1) and the liquid stream S2 comprising PA (1); wherein (iii.1.1) preferably comprises contacting water with the mixture MP obtained according to (ii), and passing MP with water into the solid-liquid separation subunit SU1 comprised in SU to remove solids contained in MP, obtaining a liquid mixture MP1 which is lean in solids compared to MP.
  9. 9. The process of any one of claims 1 to 8, wherein (iii.2) comprises subjecting the stream S2 obtained according to (iii.1) to distillation in a distillation unit comprised in PU to obtain epsilon-caprolactam separated from S2; Wherein (iii.2) preferably comprises (Iii.2.1) subjecting the stream S2 obtained according to (iii.1) to distillation in a first distillation column D1 comprised in the distillation unit, obtaining a bottom stream S2 (1) comprising epsilon-caprolactam and one or more compounds other than epsilon-caprolactam and a top stream S2 (2) comprising water; (iii.2.2) subjecting the bottom stream S2 (1) obtained according to (iii.2.1) to distillation in a second distillation column D2, D2 being located downstream of D1, obtaining a bottom stream S2 (11) comprising the one or more compounds other than epsilon-caprolactam and a top stream S2 (12) comprising epsilon-caprolactam; Or wherein (iii.2) preferably comprises (Iii.2.1 ') subjecting the stream S2 obtained according to (iii.1) to distillation in a distillation unit comprised in a PU which is a divided wall distillation column, obtaining a bottom stream S2 (1') comprising one or more compounds other than epsilon-caprolactam, an intermediate stream S2 (2 ') comprising epsilon-caprolactam and a top stream S2 (3') comprising water.
  10. 10. The method of any one of claims 1 to 8, wherein (iii.2) comprises (Iii.2.1 ") subjecting the stream S2 obtained according to (iii.1) to crystallization in a crystallization unit CU comprised in the PU, obtaining crystalline epsilon-caprolactam; wherein the crystallization according to (iii.2.1 ") is carried out at a temperature preferably in the range of 5 ℃ to 70 ℃; wherein, preferably, according to (iii.2.1 "), in addition to the crystalline epsilon caprolactam, a stream SW comprising water is obtained and removed from the CU, optionally SW is recycled as water source of (iii.1).
  11. 11. The method of any one of claims 1 to 10, wherein (iii) further comprises (Iii.3) subjecting the stream S1 obtained according to (iii.1) to an extraction with water and optionally a base B in at least one extraction zone Z E to obtain a liquid stream S11 comprising PO (1) depleted in epsilon caprolactam compared to S1 and an aqueous liquid stream S3 comprising epsilon caprolactam dissolved in water; (iii.4) separating epsilon caprolactam from the liquid stream S3 obtained according to (iii.3) in a purification unit, preferably the purification unit PU used in (iii.2).
  12. 12. A process for preparing a polymer or polymer product comprising the step of recovering epsilon caprolactam from a solid material W according to claim 11, and (Iv) Converting the liquid stream S1 obtained according to (iii.2) or the liquid stream S11 obtained according to (iii.3) as defined in claim 14 into a polymer or a polymer product.
  13. 13. A process for preparing a polymer or polymer product, comprising the step of converting at least one monomer, preferably obtained from the liquid stream S1 obtained according to (iii.2) or the liquid stream S11 obtained according to (iii.3) as defined in claim 14, into a polymer or polymer product; Wherein the monomer is preferably a diol or a polyol, preferably butanediol, an aldehyde, preferably formaldehyde, a diisocyanate or polyisocyanate, preferably methylene diphenyl diisocyanate (MDI), polymeric methylene diphenyl diisocyanate (pMDI), toluene Diisocyanate (TDI), hexamethylene Diisocyanate (HDI) or isophorone diisocyanate (IPDI), an amide, preferably caprolactam, an olefin, preferably styrene, ethylene and/or norbornene, an alkyne, (di) ester, preferably methyl methacrylate, a mono or di acid, preferably adipic acid or terephthalic acid, a diamine, preferably hexamethylenediamine, nonylenediamine, or a sulfone, preferably 4,4' -dichlorodiphenyl sulfone; Wherein the polymer is and/or the polymer product preferably comprises a Polyamide (PA), preferably PA6 or PA66, a polyisocyanate polyaddition product, preferably Polyurethane (PU), thermoplastic Polyurethane (TPU), polyurea or Polyisocyanurate (PIR), low Density Polyethylene (LDPE), high Density Polyethylene (HDPE), polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyvinyl acetate (PVA), polystyrene (PS), polyacrylonitrile butadiene styrene (ABS), polystyrene acrylonitrile (SAN), polyacrylate styrene acrylonitrile (ASA), polytetrafluoroethylene (PTFE), poly (methyl acrylate) (PMA), poly (methyl methacrylate) (PMMA), polybutadiene (BR, PBD), poly (cis-1, 4-isoprene), poly (trans-1, 4-isoprene), polyoxymethylene (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polybutylene adipate co-terephthalate (PBAT), polyester (PEs), polyethersulfone (PESU), polyhydroxyalkanoate (PHA), poly-3-hydroxybutyrate (P3 HB), poly-4-hydroxy butyrate (phhb), poly (PHV-4-hydroxy butyrate) and poly (PHV-4-hydroxy-hexanoate), polyhydroxyoctanoate (PHO), polylactic acid (PLA), polysulfone (PSU), polyphenylsulfone (PPSU), polycarbonate (PC), polyetheretherketone (PEEK), poly (p-phenylene oxide) (PPO), poly (p-phenylene ether) (PPE), or copolymers or mixtures thereof; wherein the polymer and/or the polymer product obtained according to (iv) is preferably or is part of: -automotive parts, preferably cylinder head covers, engine hoods, housings for charge air coolers, charge air cooler baffles, air inlet pipes, inlet manifolds, connectors, gears, fan wheels, coolant tanks, housings, housing parts for heat exchangers, coolant coolers, charge air coolers, thermostats, water pumps, radiators, fasteners, parts for battery systems of electric vehicles, dashboards, steering column switches, seats, head rests, center consoles, transmission parts, door modules, A, B, C or D column covers, spoilers, door handles, exterior rear view mirrors, windshields, windshield wiper protection housings, decorative grilles, cover strips, roof rails, window frames, antenna panels, headlights and taillights, cylinder head covers, inlet manifolds, airbags, bumpers or coatings; -a cloth, preferably a shirt, trousers, jersey, boot, shoe, sole, tights or jacket; -electrical parts, preferably electrical or electronic passive or active parts, circuit boards, printed circuit boards, housing parts, foils, wires, switches, plugs, sockets, power distributors, relays, resistors, capacitors, inductors, bobbins, lamps, diodes, LEDs, transistors, connectors, voltage regulators, integrated Circuits (ICs), processors, controllers, memories, sensors, micro-switches, micro-buttons, semiconductors, reflector housings for Light Emitting Diodes (LEDs), fasteners, gaskets, bolts, strips, slide-in guides, screws, nuts, film hinges, spring hooks (snap-in) or spring tongues of electrical or electronic parts; -consumer, agricultural or pharmaceutical products, preferably tennis strings, rock climbing ropes, bristles, brushes, artificial grass, 3D printed filaments, mowers, zippers, hook and loop fasteners, paper machine cloths, extrusion coatings, fishing lines, fishing nets, offshore lines and ropes, vials, syringes, ampoules, bottles, sliding elements, spindle nuts, chain conveyors, sliding bearings, rollers, wheels, gears, rollers, ring gears, screws and spring dampers, hoses, pipes, cable jackets, sockets, switches, cable ties, fan wheels, carpets, cosmetic boxes or bottles, mattresses, cushioning, insulation, detergents, dishwasher detergent blocks or powders, shampoos, body washes, shower gels, soaps, fertilizers, fungicides, or pesticides; Packaging for the food industry, preferably a single-layer or multi-layer blown film, a single-layer or multi-layer cast film, a biaxially stretched film, or a laminated film, or Structural parts, preferably rotor blades, insulating material, frames, shells, walls, coatings, or partition walls.
  14. 14. The process of any one of claims 1 to 13, wherein the liquid stream S1 obtained according to (iii.2) derived from the solid material W, or the liquid stream S11 obtained according to (iii.3) of claim 14, or the recycle content in the monomer, the polymer or the polymer product obtained according to (iv) of any one of claims 15 to 18 is 1 wt-% or more, preferably 2 wt-% or more, more preferably 5 wt-% or more, more preferably 15 wt-% or more, more preferably 30 wt-% or more, more preferably 40 wt-% or more, more preferably 60 wt-% or more, more preferably 80 wt-% or more, more preferably 90 wt-% or more, more preferably 95 wt-% or more, or Wherein the recycle content in the product stream comprising the liquid stream S1 obtained according to (iii.2) from the solid material W, or the liquid stream S11 obtained according to (iii.3) of claim 14, or the monomer, the polymer or the polymer product obtained according to (iv) of any of claims 15 to 18 is 100 wt-% or less, preferably 95 wt-% or less, more preferably 90 wt-% or less, more preferably 50 wt-% or less, more preferably 25 wt-% or less, more preferably 10 wt-% or less, and Preferably, wherein the recycle content is determined based on a source reservation and/or separation and/or mass balance and/or certificate declaration chain of custody model, more preferably based on mass balance, more preferably international sustainable development and carbon certification (ISCC) standards.
  15. 15. A unit for carrying out the recycling process of any one of claims 1 to 14, the unit comprising -A pyrolysis reactor unit RU (P); -inlet means for introducing W into RU (P); -an outlet means for removing MP from RU (P); -a separation unit SU; -an ingress device for introducing MP into SU; -outlet means for removing S1 from MP; -outlet means for removing S2 from the MP; -a purification unit PU; -inlet means for introducing S2 into the PU; -outlet means for removing epsilon-caprolactam from PU; The unit preferably further comprises -At least one extraction zone ZE comprising means for extraction; -inlet means for introducing S1 into Z E ; -outlet means for removing S11 from Z E ; -outlet means for removing S3 from Z E ; -inlet means for introducing S3 into the PU.

Description

Recycle process for recovery of epsilon-caprolactam from solid material The invention relates to a recycling process for recovering epsilon caprolactam from a solid material W comprising polyamide 6, which process comprises pyrolyzing the solid material W and subsequently subjecting it to further treatment to recover valuable epsilon caprolactam. Currently, plastic waste is still mostly landfilled or incinerated to generate heat. Chemical recycling is an attractive way to convert waste plastic material into useful chemicals. An important technique for chemical recycling of plastic waste is pyrolysis. Pyrolysis is the thermal degradation of plastic waste in an inert atmosphere and produces value added products such as pyrolysis gas, liquid pyrolysis oil, and char (residues), with pyrolysis oil being the primary product. Pyrolysis gas and char may be used as fuel to generate heat, for example for reactor heating purposes. Pyrolysis oil may be used as a source of synthesis gas production and/or processed into chemical feedstocks, such as ethylene, propylene, C4 fractions, etc., for example in a (steam) cracker. Typically, the plastic waste is a mixed plastic waste composed of different types of polymers. The polymers are typically composed of carbon and hydrogen in combination with other elements such as chlorine, bromine, fluorine, sulfur, oxygen and nitrogen, which complicate the recycling work. Elements other than carbon and hydrogen may be detrimental during further processing of the crude pyrolysis oil because they may deactivate or poison or cause corrosion of catalysts used in the further processing of the pyrolysis oil. In mixed plastic waste, polyamide, such as polyamide 6, is often present. Such polyamides 6 are valuable and the ability to recover their monomer epsilon caprolactam from mixed plastic waste is of great interest at present. It is therefore desirable to provide a recycling process for recovering epsilon caprolactam from a solid material W comprising polyamide 6. In fact, there is a need to recover valuable products that can be reused in industry while degrading solid waste, while using economical methods. WO 2023/144338 A1 and WO 2023/144339 A1 relate to processes for recovering caprolactam from a fishing net comprising polyamide 6. WO 2023/144337 A1 relates to a process for recovering epsilon caprolactam from a multicomponent material comprising nylon 6, in particular a multilayer film. Further, D3 relates to an apparatus configured to perform the method. D4 discloses a process for depolymerizing nylon 6 and recovering caprolactam from the depolymerized product by extraction with alkylphenol compounds. US 5 990 306A relates to a process for preparing purified caprolactam, which process comprises depolymerizing a polyamide containing carpet. Perez Barbara Alejandra et al ,"Insights into co-pyrolysis of polyethylene terephthalate and polyamide 6 mixture through experiments, kinetic modelling and machine learning [ "by experiment, kinetic modeling and machine learning insight into co-pyrolysis of polyethylene terephthalate and polyamide 6 mixtures," CHEMICAL ENGINEERING Journal [ Journal of chemical engineering ], volume 468, 143637 (2023) relates to pyrolysis of polyethylene terephthalate (PET), polyamide 6 and mixtures thereof. The object of the present invention is to provide a recycling process for recovering epsilon caprolactam from a solid material W comprising polyamide 6, preferably from solid waste, to recover valuable products which can be reused in industry, while using an economical process. In accordance with the present invention, it was found that the process of the present invention allows recycling of solid material W comprising polyamide 6 by efficient recovery of epsilon-caprolactam from pyrolysis liquid. The present invention thus relates to a recycling process for recovering epsilon-caprolactam from a solid material W comprising polyamide 6, the process comprising (I) Providing the solid material W; (ii) Subjecting the solid material W provided according to (i) to a pyrolysis, preferably anhydrous, in a pyrolysis reactor unit RU (P), obtaining a mixture MP comprising: An aqueous phase PA (1) comprising epsilon-caprolactam, -An organic phase PO (1) comprising epsilon-caprolactam; (iii) Separating epsilon caprolactam from MP obtained according to (ii), (iii) comprising (Iii.1) passing the mixture MP obtained according to (ii) into a separation unit SU obtaining a liquid stream S1 comprising PO (1) and a liquid stream S2 comprising PA (1); (iii.2) separating epsilon caprolactam from the liquid stream S2 obtained according to (iii.1) in a purification unit PU. The invention therefore also relates to a process for preparing a polymer or a polymer product, comprising the step of recovering epsilon caprolactam from a solid material W according to the above process, and (Iv) Converting the liquid stream S1 obtained according to (iii.2) or the liquid stream S11 obtained accordi